Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h, w = [int(s) for s in input().split(' ')]
 
s = []
for i in range(h):
    s.append([s == '.' for s in input()])
 
inf = 10000
dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]

queue = [(0, 0)]
p = []
for i in range(h):
    p.append([inf] * w)
p[0][0] = 1
 
while len(queue) > 0:
    x, y = queue.pop()
    for i in range(4):
        xx = x + dx[i]
        yy = y + dy[i]
        if 0 <= xx and xx < w and 0 <= yy and yy < h and s[yy][xx] and p[yy][xx] > p[y][x] + 1:
           p[yy][xx] = p[y][x] + 1
           queue.insert(0, (xx, yy))
           
if p[h-1][w-1] == inf:
    print('-1')
else:
    print(sum(sum(x) for x in s) - p[h-1][w-1])